In recent years, the popularization of user terminals (so-called dual terminal) that support communication schemes of both WLAN communications and cellular communications is in progress. Moreover, WLAN access points managed by operators of cellular communication systems are increasing.
3GPP (3rd Generation Partnership Project), which is a standardization project of cellular communication systems, is planning to consider techniques capable of enhancing the interworking between cellular communication systems and WLAN systems in the level of radio access networks (RAN) (see Non-patent document 1).
On the other hand, in order to achieve efficient access point discovery processes performed by user terminals, the standardization of ANDSF (Access Network Discovery and Selection Function) is currently in progress. In ANDSF, ANDSF servers provided in core networks provide information regarding the WLAN to user terminals by NAS (Non Access Stratum) messages.